Long Wharf Flood Protection Study and Living Shoreline Design

Challenge

The Long Wharf area of New Haven, located within FEMA VE and AE high risk flood hazard zones, is highly vulnerable to coastal flooding. It has historically experienced severe flooding and flood damage from hurricanes and extreme weather events dating to the Hurricane of 1938 and more recently during Hurricane Irene and Superstorm Sandy. Improved resilience to coastal flooding is imperative to the social, economic and ecological resilience of the City of New Haven and the region. GZA’s planning and design team included Utile, Biohabitats, and Cambridge Systematics.  

Solution

GZA was retained by the City of New Haven's Plan Department to implement a flood protection study of the Long Wharf district, facilitating the district’s resilience to the impacts of sea level rise (SLR), coastal flooding, and erosion. The district comprises two distinct areas in terms of character and use: the waterfront shoreline and the commercial/industrial district.  

The Long Wharf Flood Protection Study included planning and design of coastal flooding mitigation and shoreline protection measures for the area located northwest of the Long Wharf shoreline to Union Avenue. An interdisciplinary team led by GZA completed a detailed flood vulnerability analysis in the project area.  Based on the results of the vulnerability analysis, the team identified flood mitigation strategies that not only addressed economic concerns related to business disruption after flooding; but also identified ways the flood mitigation alternatives could benefit the public by creating a visionary District Plan for the City to improve social, economic, and ecological resilience to sea level rise, local intense precipitation, storm surge, and erosion. This plan also creates a renewed level of public access and recreation along the shoreline.

GZA’s project approach was multidisciplinary, and the team:

• Performed statistical analysis on historical storm surge flood level data from relevant water level stations, such as those from National Oceanic and Atmospheric Administration (NOAA);
• Used high resolution terrain data (post-Sandy);
• Completed high resolution, hydrodynamic computer flood modeling to characterize coastal flooding and its effect on structures and natural features;
• Created scenario-based flood maps to evaluate the vulnerability of the area to tides and storm surges;
• Managed all information using Esri ArcGIS geographic information system (GIS) software;
• Used a “risk-based” approach, defining coastal flood hazards in terms of probability, consistent with methods currently being used by state and federal agencies; and
• Identified resiliency strategies and alternatives that are consistent with City of New Haven’s current vision and plans for development.

Connecticut DEEP approved $4 million in state bond funding for the City to advance the flood mitigation project. The design incorporates an integrated approach to flood protection, shore protection, and environmental and ecological benefits, including a seawall, a buried revetment, a timber walkway, wetland enhancement, tidal flats, a living shoreline and submerged oyster reef breakwaters. GZA received state and federal permit approvals for the living shoreline in 2024. The comprehensive planning and flood modeling enabled the USACE to continue planning for design of a flood wall. 

Benefit

GZA’s planning and design team’s efforts enabled the USACE and FEMA to invest $185 million in 2022 with the City to construct a living shoreline and a district flood protection system. GZA’s permit-level design for the living shoreline and benefit cost analysis for the Long Wharf study area  enabled the City of New Haven to move forward in 2023 with final design and construction as federal funding was secured.  The comprehensive planning analysis and design acknowledge that a resilient New Haven waterfront is critical to Connecticut’s economy and creates the resiliency features necessary to foster social, economic, and ecological health of the Long Wharf District. The district flood protection system is scheduled to be completed in 2028.